Obesity and diabetes are reaching epidemic proportions in the USA, EU, Japan and developing countries. Obesity is the major driver of the co-morbidities of the metabolic syndrome, particularly type 2 diabetes.
Since no effective pharmacotherapies for obesity are available to date and current diabetes therapies do not stop the progression of the disease, there is a huge unmet medical need.
Fatty Acid Synthase (FAS) is a critical enzyme for endogenous lipogenesis and plays an important role in the modulation of key intermediates of lipid and carbohydrate cellular metabolism. FAS is highly expressed in the tissues with high metabolic activity (for example liver, adipose tissue and brain) and there are good reasons to believe that a FAS inhibitor would cause beneficial metabolic effects in peripheral tissues. In addition, inhibition of FAS in the hypothalamus may result in reduced food intake. The non-specific irreversible FAS inhibitors cerulenin and C-75 have been reported in the literature to decrease brain levels of orexigenic neuropeptides and to decrease food intake.
FAS is also highly expressed in human sebocytes, the lipid producing cells of the sebaceous glands. Acne is the most common disorder involving the sebaceous gland. The pathogenesis of acne involves lipid (over)production by the sebaceous gland and it has been reported that inhibitors of mammalian FAS inhibit the production of sebum in sebocytes (US 2005/0053631). Acne cannot occur without sebum lipids. There is an unmet medical need in the treatment of acne for agents that reduce sebum production.
Since fatty acid synthesis in bacteria is essential for cell survival, bacterial FAS (type II synthase) has emerged as a potential target for antibacterial therapy. Unlike in most other prokaryotes, fatty acid synthase activity in mycobacteria is carried out by a single high-molecular-weight, multifunctional peptide chain (type I synthase) related to mammalian FAS. Mycobacterial type I FAS has been described as a potential target for antimycobacterial therapy, e.g. the treatment of tuberculosis. With one-third of the world's population being infected with the tuberculosis bacillus, and multidrug-resistant strains of Mycobacterium tuberculosis developing, there is a high medical need for novel tuberculosis therapies. (Silvana C. Ngo, et al.: Inhibition of isolated Mycobacterium tuberculosis Fatty Acid Synthase I by Pyrazinamide Analogs; Antimicrobial agents and Chemotherapy 51, 7 (2007) 2430-2435)
Recently, microdomains of organelle membranes rich in sphingomyelin and cholesterol (called “lipid rafts”) have been considered to act as a scaffold for the hepatitis C virus (HCV) replication complex (F. Amemiya, et al.: Targeting Lipid Metabolism in the Treatment of Hepatitis C Virus Infection. The Journal of Infectious Diseases 197 (2008) 361-70). Consequently, alterations of membrane lipid composition and/or distribution may influence viral replication. Indeed, agents related to lipid metabolism like polyunsaturated fatty acids or HMG-CoA reductase inhibitors (statins) have been shown to affect the replication of genotype 1 HCV (dto). These agents may attenuate HCV replication through the destruction of lipid rafts, according to their pharmacological actions. An alternative molecular mechanism possibly responsible for the inhibition of HCV replication is via altering localization of host proteins through alterations in lipid anchoring (S. M. Sagan, et al.: The influence of cholesterol and lipid metabolism on host cell structure and hepatitis C virus replication. Biochem. Cell Biol. 84 (2006) 67-79).
Unlike polyunsaturated fatty acids, addition of saturated fatty acids or oleic acid to cultured SfiI cells promoted HCV RNA replication (S. B. Kapadia, F. V. Chisari: Hepatitis C virus RNA replication is regulated by host geranylgeranylation and fatty acids. PNAS 102 (2005) 2561-66). In line with this, it has been reported that expression of fatty acid synthase was increased in a human hepatoma cell line upon HCV infection (W. Yang, et al.: Fatty acid synthase is up-regulated during hepatitis C virus infection and regulates hepatitis C virus entry. Hepatology 48, 5 (2008) 1396-1403). Furthermore, inhibition of fatty acid biosynthesis by TOFA (an inhibitor of acetyl-CoA carboxylase) or inhibitors of fatty acid synthase (cerulenin, C75), led to decreased HCV production (dto).
The effect of fatty acid synthase (FAS) activity on viral replication or infection appears not to be restricted to HCV, but has also been reported for HIV (D. H. Nguyen, D. D. Taub: Targeting Lipids to Prevent HIV infection. Molecular Interventions 4, 6 (2004) 318-320), Poliovirus (R. Guinea, L. Carrasco: Effects of Fatty Acids on Lipid Synthesis and Viral RNA Replication in Poliovirus-Infected Cells. Virology 185 (1991) 473-476), Epstein-Barr virus (Y. Li., et al.: Fatty acid synthase expression is induced by the Epstein-Barr virus immediate-early protein BRLF1 and is required for lytic viral gene expression. Journal of Virology 78, 8 (2004) 4197-4206), human papilloma virus (L. Louw, et al.: HPV-induced recurrent laryngeal papillomatosis: fatty acid role-players. Asia Pac J Clin Nutr 17 (51) (2008) 208-211), coxsackievirus B3 (A. Rassmann, et al.: The human fatty acid synthase: A new therapeutic target for coxsackievirus B3-induced diseases? Antiviral Research 76 (2007) 150-158), Rous sarcoma virus (H. Goldfine, et al.: Effects of inhibitors of lipid synthesis on the replication of Rous Sarcoma Virus. A specific effect of cerulenin on the processing of major non-glycosylated viral structural proteins. Biochimica et Biophysica Acta 512 (1978) 229-240), as well as human cytomegalovirus (HCMV), and influenza A virus (J. Munger, et al.: Systems-level metabolic flux profiling identifies fatty acid synthesis as a target for antiviral therapy. Nature Biotechnology 26 (2008) 1179-1186).
Taken together, there is growing evidence, that activity of the host's FAS plays an important role in viral infection and viral replication, suggesting FAS as a target for antiviral therapy.
The expression of FAS is strongly increased in many cancers and there is evidence that efficient fatty acid synthesis is required for tumor cell survival. Inhibition of FAS has therefore been suggested as a new direction for oncology (Expert Opin. Investig. Drugs 16, 1 (2007)1817-1829).